This invention relates to improvements in the manufacture of multi-ply fibrous sheet structures, particularly of the soft absorbent type such as, for example, paper towels.
In the manufacture of paper towels, efforts have been directed to improving important product qualities such as softness, water absorbency, and bulk. Softness, absorbency, and a degree of bulk have been imparted to multi-ply fibrous sheet structure by provision of highly repetitive patterns of relatively closely spaced emboss elements in confronting plies. For aesthetics, a further desirable product quality, color patterns larger than the emboss elements have been applied. Softness, absorbency, bulk, and aesthetics have been enhanced by application of decorative, relatively widely spaced spot emboss elements to confronting non-embossed creped plies, with or without application of color.
The following documents are representative of the prior art, and are believed material to the Examination of this application:
U.S. Pat. No. 2,834,809 discloses embossing rolls 22, 23 having meshed protuberances 24 and depressions 25 for embossing a single ply of base stock 21 to form absorbent paper 20.
U.S. Pat. No. 3,556,907 discloses rolls 12, 13 for embossing separate plies 15 and 23 to form meshed embosses 17 and 25.
U.S. Pat. No. 3,673,060 discloses creped tissue webs joined by adhesive spots 34 upon passage between laminating rolls 28, 30. The joined webs are embossed upon passage between embossing rolls 31, 32.
U.S. Pat. No. 3,775,231 discloses identical embossments A, B, and C formed by passing a web 10 through three embossing stations defined by rubber rolls 13, 15, or 16 disposed about a single embossing roll 12.
Copending U.S. Patent application of the present inventor, Ser. No. 116,230, filed Jan. 28, 1980, a continuation of abandoned application Ser. No. 1,741, filed Jan. 8, 1979, now abandoned and assigned to the assignee of the present invention, discloses a spot emboss pattern applied to one side of a multi-ply fibrous sheet structure.
It is an objective of the present invention to provide a multi-ply fibrous sheet structure characterized by improved softness, absorptivity, bulk, and aesthetics through inclusion of a novel combination of relatively small, closely spaced emboss elements with relatively large, less closely spaced spot emboss elements.
It is a further objective of my invention to provide an improved method and apparatus for forming multi-ply fibrous sheet structure of improved absorptivity, softness, bulk and aesthetics.